The present invention relates to a catheter or to a microcatheter or to a guidewire for macerating a thrombus and to a method for thrombus maceration with the catheter or the microcatheter or the guidewire.
Guidewires have had use in procedures such as percutaneous transluminal coronary angioplasty (PTCA), and as mechanisms for advancing a catheter to a treatment site within a blood vessel. In one type of procedure, a guiding catheter is introduced into a patient's arterial system and is advanced to an ostium of the patient's diseased artery. A guidewire has been used with the guiding catheter in over-the-wire procedures wherein the guidewire is preloaded with an inner lumen of a dilatation catheter. Both the dilatation catheter and the guidewire are advanced through the guiding catheter to a distal end of the guiding catheter. The guidewire is advanced out of the distal end of the guiding catheter into the artery.
A physician may shape the distal end of the guidewire to facilitate guiding it through coronary anatomy to a diseased region. When the guidewire is in a desired position, the dilatation catheter is advanced out of the guiding catheter over the guidewire where it may be activated when properly positioned.
Guidewires may be fixed or may be built in to a steerable catheter. Guidewires typically include an elongated core member with a flexible helical coil secured to a distal extremity of the core member. The core member can extend to the distal end of the coil and can be secured thereto. Alternately, the distal extension of the core element can terminate short of the distal end of the coil and a shaping ribbon can extend to the distal end of the coil and can be secured by its distal end thereto. The ribbon may be secured by soldering or brazing to the core element.
The Kotula et al. Pat. U.S. No. 5,569,275, issuing Oct. 29, 1996, describes a thrombus macerating device that includes an elongate, flexible shaft which can be guided along a vascular path. A rotor or impeller with blades is affixed to the shaft adjacent to its distal end. A drive mechanism is provided for rotating the shaft and the rotator which is attached to the shaft. The rotor is retained within a rotor housing and rotates within the housing. The rotor housing includes a cylindrical wall that surrounds the rotor and that has at least three ports spaced angularly about the circumference of the housing. As the rotor is rotated, it will tend to draw blood into the housing in a proximal direction and expel the blood out through the ports. The blood then tends to be drawn back into the distal end of the housing and through the rotor again. This movement sets up a recirculating vortex which repeatedly passes the blood across the blades.
When the blood is ejected through the ports in the housing within a vascular channel, the blood will act against the wall of the channel. This action maintains the housing in a position which is faced away from the surrounding vascular wall. By spacing the ports angularly about the circumference of the housing, the force exerted by the ejected blood tends to maintain the housing and rotor carried within the housing in a position that is centered within a vascular channel.
The Kotula et al. Pat. U.S. No. 5,284,486, issuing Feb. 8, 1994, describes a mechanism for breaking down a thrombus with rotating blades. The thrombus is broken down into particles which are fine enough to be left in the vascular system without a significant risk of forming additional thrombi. The mechanism also includes another mechanism to ensure that rotating blades of the mechanism do not directly contact walls of a vessel, but remain centered within the vessel. The mechanism includes an elongate, flexible shaft with a rotor or impeller having blades affixed to the shaft adjacent its distal end. A drive mechanism is provided for rapidly rotating the shaft and the rotor attached to the shaft. The rotor is retained within a rotor housing and rotates within the housing. The rotor housing includes a generally cylindrical wall that is substantially surrounding the rotor and that has at least three ports spaced angularly about the circumference of the housing. As the rotor is rotated, it will tend to draw blood into the housing in a proximal direction and expel the blood out through the ports. The blood then tends to be drawn back into the distal end of the housing and through the rotor again. This activity sets up a recirculating vortex which repeatedly passes the blood across the blades.
The thrombus may also be dissolved because the thrombus is comprised of components that can be dissolved or "lysed" with drugs such as TPA and Urokinase. In conventional stroke therapy, TPA is administered via a systemic intravenous (I.V.) Administration. The drugs are infused throughout the entire circuitry system so that only a very diluted concentration of drug actually contacts the thrombus.